Have you ever wondered why the gang’s favorite spot — the legendary orange sofa — was always available for them? Look closely, and you’ll notice that it’s been reserved! You can see the sign in a couple of early episodes. The sign is missing in some episodes, but there’s no need to leave the "Reserved" sign for regulars, right?

In the pilot, after leaving Barry at the altar, Rachel comes to the coffee house where Monica introduces her to Joey, Phoebe, and Chandler. But a couple of episodes later in "The One With the Flashback," we’ll find out that Rachel and Chandler know each other from college and Thanksgiving dinners at the Gellers.

Monica has always been very demanding. However, she was also trying to deal with her problem: at Alessandro’s she had a special jar in which she had to put a dollar every time she yelled at somebody. Apparently, she did yell. A lot.

Everybody saw a window in Monica’s apartment, but few of us noticed that the scene outside this magical kitchen window was constantly changing. A brick wall, a nearby building... We did like the apartment, but there was something really weird going on with this particular window.

Throughout the series, the Magna Doodle Board on Joey and Chandler’s apartment door carried a lot of funny messages. For example, when Chandler and Monica confessed they were dating, a cute drawing of a heart with their initials appeared on the board (aww, how sweet of you, Joe!). Chandler also used to leave messages for Joey to call back some girl, his agent, or his dad.

On the first episode of season 6, they added "Arquette" to the end of everyone’s names in the credits to congratulate the happy couple, David and Courteney, who changed her name to Courteney Cox Arquette.

While others were getting older, Ross didn’t age for three entire seasons. He mentioned he was 29 at least in seasons 3, 4, and 5. Plus, according to Dr. Geller, he was born in December. A couple of years later, he claimed that his birthday was October 18th. We believe it must be the power of Unagi.

Everybody loves Chandler’s jokes and sarcastic comments. Well, except for his closest friends. The only logical explanation we could think of is that the director didn’t want to ruin the flow of the scene by stopping for laughs. Yeah, not fair, Chandler, but we know you’re "the funny one."

Do you remember Joey’s agent, Estelle Leonard? Few recognized her when she played the role of a nurse in the episode in which Ross’s son, Ben, was born.

In “The One With the Secret Closet,“ they showed us the ”4th wall" of Monica’s apartment while Chandler was attempting to open the secret closet. It was a unique opportunity to see the angle used by the camera crew to shoot the majority of scenes.

Remember the episode in which Monica picks up Emily’s wedding dress and ends up trying it on with her girlfriends who, by the way, also put on wedding gowns? We don’t know why, but Emily wears a completely different dress during her wedding. Rachel’s dress also went through some changes since she left her fiancé at the altar in season 1.

When Lisa Kudrow got pregnant, screenwriters decided to incorporate her pregnancy into the Friends script. Voilà! Phoebe got pregnant too! But it was much more difficult when Courteney Cox announced her pregnancy. According to the plot, Chandler and Monica can’t have children and they adopt twins. Although Courteney was wearing baggy clothes all the time, we still can notice her growing belly in some episodes.